Ratchet



Nov. 21, 1967 w. F. DONOVAN 3,353,454

RATCHET Filed April 5, 1966 gwu /wtm WIL HAM E DON OVAN United States Patent 3,353,454 RATCHET William F. Donovan, Aberdeen, Md., assignor to the United States of America as represented by the Secretary of the Army Filed Apr. 5, 1966, Ser. No. 540,417 3 Claims. (Cl. 925) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to ratchets, and more particularly, to an hydraulic ratchet.

The attributes of a mechanical ratchet with its spring loaded pawl and engaging teeth are limited by the axial spacing of the teeth, the circumferential spacing of the pawl and the associated stress and material conditions impossed by the limited space requirements.

One of the objects of the invention is to provide a simple mechanical arrangement or mechanism wherein a work-producing member is driven along an axis of motion to infinitely variable locked positions.

Another object of the invention is to provide such an arrangement in which the member maintains a 360 sealing relationship with a complementary support structure.

These and other objects, advantages and features will become more apparent from the following description and accompanying drawings in which:

FIG. 1 is a partial sectional view of an arrangement in its starting position and embodying the principles of the invention.

FIG. 2 is a view similar to FIG. 1 with the part in a first stroke position.

FIG. 3 is a view similar to FIG. 2 with the parts in a return position.

FIG. 4 is an enlarged view of a portion of the FIG. 1. arrangement.

The hydraulic ratchet or work arrangement of FIG. 1 includes a cylinder whose sidewall 11 has an inwardly extending annular flange 12 integral with a rearward portion thereof. Power piston 13 has a substantially hollow main body portion 14, an outwardly extending rear flange portion 15, and a forward enlarged head portion 16 Whose external lateral surface contains an annular recess 17 containing an appropriate fluid sealing O-ring 18 that slidably engages the inner surface of the cylinder sidewall 11. A suitable compression spring 20 is positioned intermediate the power piston rear flange and the cylinder flange 12 to normally bias the power piston 13 rearwardly of the preferably fixed cylinder wall 11.

A fluid drive piston 21 has a main body portion 22 extending a substantial distance within the hollow piston 13 and an enlarged forward head portion 23 whose lateral surface has an annular groove 24 carrying O-ring 25 for engagement with cylinder sidewall 11 forwardly of power piston head 16.

Preferably, the power piston head 16 is provided with an internal annular groove 26 carrying O-ring 27 for engaging the main body portion 22 of intermost piston 21. As seen in FIG. 4, groove 26 has a rearward tapering sidewall portion that includes a plurality of segmental tapers 28, 29 which gradually increase in slope, such that O-ring 27 is deformed (FIG. 2) as a driving coupling between and to lock pistons 13 and 21 together during forward movement of the piston 13. Groove 24 of piston 21 has a similar forward tapering surface portion to deform and lock its O-ring 25 (FIG. 3) against cylinder sidewall 11 to prevent rearward movement of the piston 21 at all times and especially when the other of the telescoping pistons is being withdrawn to its initial position by return spring 20 at which time O-ring 27 re-assumes its normal sliding and sealing condition.

Cylinder flange 12 is suitably grooved at its inner periphery to carry O-ring 19 which sealingly engages hollow piston portion 14 and cooperates with O-ring 18 to provide a sealed, variable sized chamber 30 around the hollow piston portion 14 between flange 12 and piston head 16.

Conduit 31 supplies desired pressurized fluid from a suitably valved or controlled pressure supply (not shown) to the chamber 30 for actuating piston 13. An appropriate pressure gauge 32 will indicate the chamber pressure at all times. Thus, the driven piston 21 may be successively or periodically advanced so as to perform its lifting, holding, or other desired work functions.

Various modifications, changes or alterations may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. In a ratchet, a cylinder having a sidewall and an inwardly extending flange integral therewith, a power piston having a substantially hollow cylindrical main body portion, outwardly extending rear flange and forward head portions, said head having an external lateral surface provided with an annular recess and an O-ring in said recess engaging an inner surface of said cylinder sidewall, spring means positioned between said power piston rear flange and said cylinder flange to normally bias said power piston relatively rearward of said cylinder, a fluid drive piston having a main body portion extending Within said power piston and an enlarged head portion with an annular lateral groove carrying an O-ring for engaging said cylinder sidewall forwardly of said power piston head, said power piston having an internal annular groove carrying an O-ring for engaging said fluid drive piston main body portion, said cylinder flange carrying an O-ring for engaging said power piston main body portion rearwardly of said power piston head internal O-ring, and means for delivering pressurized fluid into said cylinder and around said power piston main body portion intermediate said cylinder flange and power piston head to move said power piston forward, said power piston head internal groove having a rearward tapering sidewall portion to lock its O-ring between said pistons during forward movement of said power piston, and said fluid drive piston head groove having a forward tapering surface portion to lock its O-ring against said cylinder sidewall to prevent rearward movement of said fluid drive piston.

2. The arrangement in accordance with claim 1 wherein said groove tapering portions each include a plurality of segmental tapers gradually increasing in slope.

3. The arrangement of claim 1 in which a pressure gauge is mounted upon said cylinder sidewall adjacent said fluid delivering means.

References Cited UNITED STATES PATENTS 1,312,649 8/1919 Turner 92-113 X 2,259,815 10/1941 Greve 92-14 MARTIN P. SCHWADRON, Primary Examiner. I. C. COHEN, Assistant Examiner. 

1. IN A RATCHET, A CYLINDER HAVING A SIDEWALL AND AN INWARDLY EXTENDING FLANGE INTEGRAL THEREWITH, A POWER PISTON HAVING A SUBSTANTIALLY HOLLOW CYLINDRICAL MAIN BODY PORTION, OUTWARDLY EXTENDING REAR FLANGE AND FORWARD HEAD PORTIONS, SAID HEAD HAVING AN EXTERNAL LATERAL SURFACE PROVIDED WITH AN ANNULAR RECESS AND AN O-RING IN SAID RECESS ENGAGING AN INNER SURFACE OF SAID CYLINDER SIDEWALL, SPRING MEANS POSITIONED BETWEEN SAID POWER PISTON REAR FLANGE AND SAID CYLINDER FLANGE TO NORMALLY BIAS SAID POWER PISTON RELATIVELY REARWARD OF SAID CYLINDER, A FLUID DRIVE PISTON HAVING AN MAIN BODY PORTION EXTENDING WITHIN SAID POWER PISTON AND AN ENLARGED HEAD PORTION WITH AN ANNULAR LATERAL GROOVE CARRYING AN O-RING FOR ENGAGING SAID CYLINDER SIDEWALL FORWARDLY OF SAID POWER PISTON HEAD, SAID POWER PISTON HAVING AN INTERNAL ANNULAR GROOVE CARRYING AN O-RING FOR ENGAGING SAID FLUID DRIVE 